isPrime.py

# Define a function that takes an integer argument and returns a logical value true or false depending on if the integer is a prime.

# Per Wikipedia, a prime number ( or a prime ) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

# Requirements
# You can assume you will be given an integer input.
# You can not assume that the integer will be only positive. You may be given negative numbers as well ( or 0 ).
# NOTE on performance: There are no fancy optimizations required, but still the most trivial solutions might time out. Numbers go up to 2^31 ( or similar, depending on language ). Looping all the way up to n, or n/2, will be too slow.
# Example
# is_prime(1)  /* false */
# is_prime(2)  /* true  */
# is_prime(-1) /* false */

from math import sqrt
def is_prime(num):
    if num==2 or num==3:
        return True
    if num%2==0 or num<2:
        return False
    for n in range(3,int(num**0.5)+1,2):   
        if num%n==0:
            return False   
    return True